Transformer



June 2, 193.1.` f H. `R. LOUBET 1,808,570

TRANSFORMER Filed March 14. 195o 2 sneerfsheer .l

` @6213"07' lirenri Eene' L oue' H. R. LOUBET June 2, 1931.

TRANSFORMER Filed March 14, 1950 4 2 Sheets-Sheet 2 Patented June 2, 1931 UNITED STATES PATENT OFFICE HENRI REN LOUBET, OF PARIS, FRANCE, ASSIGNOR T0 COMPAGNIE POUR LA FABRICA- TION DES COMPTEURS ET MATERIEL DUSINES A GAZ, OF MONTROUGE, FRANCE, A j

JOINT-STOCK COMPANYl OF FRANCE TRANSFORMER Application led March 14,v 1930, Serial No. 435,855, and in France March 20, 1929.

Transformers the primaries of which only include a single turn formed in the majority of cases by a straight bar passing through the opening in the magnetic circuit, which transformers are commonly termed bar transformers, possess among other advantages that of only requiring for their insulation a single bushing or leading-in insulator; whence the expression bushing transfoi-mers"7 adopted for this type of apparatus. But, in their usual form, these transformers can only be designed to take currents of several hundred amps: for smaller currents, the ampere-turns becoming insufficient, such apparatus can no longer be used for feeding wattmeters and meters.

The object of the present invention is to produce a transformer possessing great accuracy and which may be designed to take a very low current, although the insulation may be formed by a single bushing insulator.

The invention is based on the principle of using an auxiliary transformer to step up the line current which may be very weak7 to such a value that when applied as the primary current a very satisfactory transformer of the bushing type is secured.

Several embodiments of the invention have been illustrated diagrammatically and by way of example in the accompanying drawings in which:

Fig. 1 illust-rates one embodiment of the bushing transformer used in conjunction with an auxiliary transformer.

Fig. 2 shows a modification of Fig. 17 using two transformers.

Figs. 3, 4, 5 and 6 are further modifications. e

Fig. 7 illustrates another modification using bushing insulators for the bushing transformer and the auxiliary transformer respectively.

Fig. 8 illustrates another modification of Fig. 1, in which the outer portion of the bar conductor is also insulated' by means of a bushing insulator.

In the embodiment illustrated in Fig. 1, T1 is the auxiliary transformer connected to the line at P1 and P2 and the magnetic circuit of which is in the form of a torus about which is wound N turns of the primary winding p through which flows the line current.

The bushing transformer has been comprehensively designated T2 and is carried by a flange B mounted on a suitable support S.

The insulation for the transformer T2 takes the form of the bushing insulator I, supporting at its upper end the auxiliary transformer Tl and passing through an opening in the magnetic circuit of the transformer T2, which auxiliary transformer.` The bar C is rcctilinear in form over the portion thereof passing through the two transformers T1 and T2. Outside said transformers, it is bent round to form roughly a semi-circle so that the air gap Lc between it and the flange B shall be sufficient for the voltage involved, the flange B being at .the potential of the torus T2 Whereas, as will be seen presently, said conductor C is at the line high tension potential similarly to the auxiliary transformer T1.

The primary winding p of the auxiliaryy transformer T is led from said transformer T, to the point A where a connection is made with a suitably insulated cable D housed in the semi-circular portion of the conductor C which is tubular and passing out therefrom to said point of connection A through the porcelain insulator E. At the point A', where the lower end of the cable D leaves the conductor C, a Contact is established between the cable and conductor, said point of contact being connected to the line at P2. It therefore follows that the primary p of the auxiliary transformer T1 is at the same potential as the conductor C.

This device operates in the following manner:

The apparatus is mounted in the line between P1 and P2. The line current flowing through the/N turns ofthe primary p of the 1 'transformers T1.

' Several'of what appear to ampere-turns of the conductor C may be,

placed on the auxiliary transformer T1 than on the bushing,transformer T2. arrangement has been illustrated in Fig. 3, whil'ein Fig. 4 has been shown the combined arrangements of Figs. Zand 3.;

Instead of a single conductorA C, several may be used in parallel or in series, an a.r. rangement in parallel being shown in Fig. 5, while Fig 6 shows this arrangement in conjunction with the use of two auxiliary be the most preferable forms of theinvention have been described, but any alternatives in which the current-is stepped up to enable it to be fed toa. bushing transformer, come Withinthe scope of the invention.

YThus the auxiliary transformer T1 might be insulated from the conductor C for a fraction or the Whole of the voltage by means of an insulator'll, while a second insulator L insulates the conductor C and the bushingV transformer T2. rlhis has been illustrated iii li`ig-7.-y Q,

ncidentally it isnot essentialthat the magnetic circuit should take the form lofa torus.

VMoreover7 as illustrated in vFig. 8, thecon-V ductor C may be likewise insulated outside the portion thereof passing through the bushing transformerV T2. Thus in Fig. 8, l2v designates vthe insulator for the bushing transformer T2 whereas l1 designates the insulator used for that portion of the conductor C situatedoutsid'e the transformer TL; lt will be seen moreover in Fig. 8 that the conductor@ has been given `a rectangular instead of a semifcirc'ular formV outside the transformer T2. Y e Y Finally the roles of the transformersV T1 and Tgjmaybe reversed. Thus 'lgwill be fed from thehigh tension and them'easuring apparatuswillbefed by T1; in this case 'the conductor C may be'on the low tension side.

'1; In adevice for feeding currentl to electrical measuringrapparatus, the combination i' of a' transformer'designed to take a high current, an electric circuit, a bushiiiginsulator passing through said transformer, an auxiliary transformer supportedby said bushing Lscacro primary of said first transformer and stepping up the current to the high value for which said first transformer is designed, and a secondary to said first transformer adapted to step down the current to a low value conimensurate with that taken by the electrical measuring apparatus. Y

2. ln a device for feeding current to electrical measuring apparatus, the combination of a transformer designed to take a high current, an electric circuit, a bushing insulator passing through said transformer and including a primary fed by the current iiowing iiiy said circuit, a secondary to said rst transformer formed by a straight conductor passing through said bushingv insulator, said straight conductor including a portion situated without said bushinginsulator, a second bushing insulator supporting said auxiliary transformer and being located in spaced rela- .'tion to said i'irst bushing insulator7 said conductor, Vwhich is bent round to form a. closed loop, passing through said second bushing insulator and at the same time forming the secondary of said auxiliary transformer and stepping up the line'current to the high value for which said first transformer is designed, and a secondary to said first transformer adapted to step down the current liowing in said straight conductor to a value commensurate with that taken by the electrical measuring apparatus. Y s Y l 3. In aV device for feeding current to electrical measuring apparatus, the combina tion of a transformer designed to take a high current, an electric circuit, aA bushing insulator passing through said transform i an auxiliary transformer 'including a primary fed by-'the current flowing in said circuit, a secondary to said first transformer formed by a Vstraight conductor 'passing through said bushing insulator, and bent rou-nd Voutside said bushing insulator so as to form a closed circuit, said straightconductor includinga insulator. and' including 'a prima-ry'- fed bye.

the curreiittlowing lin said circuit, asecondaryto said auxiliary transformer form-ing the cil supporting same, an auxiliary transformer Such an iio iso Y 

